Lava
a term used vaguely of all in streams from volcanic vents, but more molten matter existing within or flowing specifically confined to the latter, the former being called trap. The lower part of it which has consolidated slowly and under pressure, tends to be of stony consistency, while the upper is scoriation. Some are trachytic, as in the Peak ceous. Lavas vary greatly in composi- Vesuvius and Auvergne; others andesitic, of Teneriffe; many are basaltic, as in the most modern in Vesuvius consist of as in the volcanoes of Chile. Some of green augite, and many of those of Etna of augite and Labrador felspar. partment of Mayenne, and one of the LAVAL (lä-väl), capital of the dethe demost picturesque towns of France most picturesque towns of France, on river; 46 miles E. of Renfrom the 12th century, are the cruciform nes. Its chief buildings, both dating nes.
Its chief buildings, both dating Trémouilles (a prison now), in whose cathedral and the old ducal castle of the courtyard young Philip de la Trémouille, Prince de Talmont, was guillotined by the Republicans in 1794. Since the 13th century , when Flemish weavers settled here, the town has been the center of a district noted for its linen manufactures-linen, ticking, sacking, etc. In the vicinity the Vendeans, under Larochejaquelein gained a victory over the Republicans Republicans. a